Leveling acid or direct dyes with chlorine decolored acid or direct dye wastes

ABSTRACT

A process for treating dyehouse waste water, containing leftover dyestuff, for reclamation and reuse for consecutive dyeing and/or rinsing or the like, in which halogen, such as gaseous chlorine, is added to decolorize the chromophoric functional group of the dystuff. The decolorized waste water is then recycled into the dyeing system.

United States Patent [1 1 Las'as [451 Apr. 30, 1974 LEVELING ACID OR DIRECT DYES WITH CHLORINE DECOLORED ACID OR DIRECT DYE WASTES [76] Inventor: Longinas Lasas, 6708 W. 88th St.,

Los Angeles, Calif. 90045 [22] Filed: July 14, 1972 [21] Appl. No.: 271,967

[52] US. Cl 8/81, 210/62, 8/89,

7 8/150, 8/158 [51] Int. Cl D06p 1/68 [58] Field of Search 210/62; 8/81, 102, 150,

[56] References Cited UNITED STATES PATENTS 3,300,402 1/1967 Grich et al 210/62 OTHER PUBLICATIONS Chem Abstract, Vol. 25, 1940, C01. 4577.

Fields et al., Water Suppy & Wastewater Disposal, pages 868-870, & 879.

Primary Examiner-Donald Levy Attorney, Agent, or Firm-Nilsson, Robbins & Berliner [57] ABSTRACT 6 Claims, N0 Drawings LEVELING ACID OR DIRECT DYES WITH CI'ILORINE DECOLORED ACID OR DIRECT DYE 'WAST'ES FIELD or THE INVENTION The present invention generally relates to dyeing process and more particularly to improvements in textile dyeing processes which permit the reclamation and recycling of dyehouse waste water.

BACKGROUND AND SUMMARY OF THE INVENTION In conventional textile dyeing processes, and related dyeing processes such as those commonly used in the dyeing of leather goodsand the like, vast quantities of wastetreating solutions are produced which contain dyes. The quantities of waste water so produced are very large due to the millions of yards of goods dyed each year in a great number of plants. Such dyecontaining solutions. in the past have been merely dumped into waste disposal areassuch as streams, pits and the like.

More recently, anti-pollution measures have required cleanup of such waste waters before their disposal. Such clean-up measures usually consist of decolorizing the dyes and then precipitating the dye molecules with various chemicals and removal of solid residue. Obviously, such clean-up steps are expensive and time consuming and also may result in the formation-of certain dissolved salts and the like which may in themselves present a potential environmental hazardAccording'ly, it would behighly desirable, both from an economic standpoint and from an ecological standpoint to provide a way of treating such waste -waters'soas-toreduce or eliminate the necessity of their disposal.

As further background :to the present invention, some :details of textile dyeing operationscan be noted. The dyestuffs used in such operations bear colorimparting groups and may be non'ionic (disperse and polyester disperse), cationic or anionic (direct and acid) in nature. Other dyes such as'the vat and sulfur types are also used. Dyes of .such I chemical classifications asazo, diazo, nitro and the like havelbeen used successfully for a number of years. Various dye combinations can be used in, for example, 'polycliromatic four-tone or polyester threeatone applications. In the dyeing operation leveling dye ass'istantsareneededto slow down the colorizing rate sufficientlytoenablethe dye plant' operator'to gain precise .controlover the i intensity of shades desired. Such.levelers normally operate to preferentially and loosely attachto'the available fiber dye sites and/or react with the dye :molecules to loosely bond thereto. In each instance, affinite;period waste water discarded. In a continuous processpthey have to be added to the dye containing'itreating-agent before or during textile dyeing, since a substantial proportion of the dyePassistant isabsorbed 'by-thetextil'e during the dyeing step. Accordingly, it would-alsobe highly desirable toreduce: the expense normally-incurred in connection with theuse dfdye assistants.

The foregoing needs have been satisfied by the present invention which provides'a novel process for dyehouse water reclamation substantially as set forth above in the Abstract of the Disclosure.

Specifically, waste waters from a conventional textile dyeing process are treated in a novel manner, rather than being discarded with or without previous treatment to destroy dyes therein. In this regard, waste waters containing chromophoric dye are decolorized by a 0 suitable agent such as halogen, for example bromine,

' manner that no dyehouse waste water need be disposed of at'all. Instead, the waste water can be completely recycled in a closed loop operation to provide substantial savings in time, effort and money. The dye destruction and coagulation steps normally used can be eliminated while recovering a useful product. Moreover, the environment benefits since waste disposal is eliminated.

Accordingly, the present invention provides increased utility and economy in an important .industry.

the dyeing process and are lost with each *batch :of

Furtherxadvantages of the invention are as set forth in .the following detailed description.

DETAILED DESCRIPTION ."For present purposes, dyestuffs normally employed in the .carpet dyeing industry and in the dyeing of certain other textiles, such as clothing, leather, paper and the like, can be treated by the present invention. For example, azo dyes,-diazo.dyes, alizarin, anthraquinone and the'nitro dyes are treated. These and other types @of dyestuffs arexwell known to the art and detailed mention thereof is, therefor, not necessary. In the dyeing of carpeting, a leveling dye assistant can be employed.

Commercial brands of such agents include those sold :under the trademark TAMOL S.N. of Rohm and Haas and under the trademark LOMAR P.W. of NAPCO and are useful as make-up agents in the present process. The nature of such types of levelers is well known .to'the art.

The conventional dyeing process utilizes water in various phases, such as in the dyeing itself, in rinsing,

.incooling, in softening where necessary, etc.-ln confrom the ditch to a reclamation tank. In the reclama- .tion tank, gaseous chlorine is bubbled through the wastewater and instantly formshydrochloric acid and :hypochlorous acid in accordance with the following generalized equation:

C1 H O HCl HOCl .The hydrochloric acid (strong acid) ionizes and suppresses ionization of the hypochlorous acid (weak acid). The latter is most effective as adecolorizing agent when it is in the unionized form. Such agent decolorizes the dyestuff while keeping it otherwise intact. Accordingly, it can, if desired, perform a function of occupying textile dye sites in competition with the dye molecules to delay the striking by the dye on a textile exposed thereto. In other words, the decolorized solution can be used as a dyestuff leveling solution.

Usually, the chlorine is used in the present process in a concentration of about 0.5-1.5 pounds per about 2,500 gallons of waste water, with the higher concentrations being used with high dyestuff concentrations in the waste water. Such chlorine concentration is sufficient to efiectively decolorize the dyestuff and to cause the pH of the aqueous suspension or solution to be about pH 6.5 or less. Typical treating times are about -40 minutes. Moreover, the amount of chlorine necessary to decolorize the dyestuff can be calculated, or adjusted, to provide an amount slightly in excess thereof, all in accordance with the present invention. The pH of the resulting decolorized solution can then be adjusted, if desired, after checking with a standard type pH meter. In accordance with the invention, excess chlorine is then neutralized or destroyed with a suitable antichlor, for example, sodium bisulfite, sodium sulfite or the like.

Although chlorine has been employed in certain conventional procedures for treating waste solutions of dye, such procedures make no attempt to recycle the water solutions and, instead, employ dye moleculedestroying steps entirely avoided in the present process. Thus, in conventional processes such agents as ferric chloride, ferric sulfate and aluminum sulfate are used to coagulate and precipitate the decolorized dye. This results in a solid waste disposal problem.

it will be noted that it is desired to decolorize on the acid side. As the pH increases above about neutral pH, the decolorization reaction slows down, so that at a pH of about 9.0 and above, substantially no or little decolorization occurs. Although so-called commercial liquid chlorine can be employed in the present process, it is not preferred as the decolorizing agent. In this regard, liquid chlorine contains percent sodium hypochlorite, NaOCl, which yields a major proportion of sodium hydroxide (to provide a basic pH), is costly and unstable and yields only a minor amount of free chlorine.

After chlorine treatment and addition of antichlor, as above, the waste water is now ready to be recycled back into the dyeing system for use in place of, and as a fully satisfactory substitute for, fresh water. Thus, it can be used in the dyeing step. In this regard, as an added advantage, the amount of leveling dye assistant which must be added can be greatly reduced, or even eliminated in some cases. This results from the fact that the decolorized dyestuff retains its site seeking ability and/or competes with the dyestuff for sites. Generally, only about percent of the normal amount of dye assistant need be added. The types of dye assistant and procedures for their use depends, of course, on the type of dyestuff and fibers. Such is well known to the art and need not be set forth herein.

it will be understood from the above description that the present process can be carried out very conveniently and efficiently on an essentially closed loop basis, with little or no loss of waste water and without the usual involved and extensive waste water treatment and disposal of the thus treated waste water. The following specific example further illustrates certain features of the present invention.

I Example A textile carpet dyeing process for dyeing 1,500 lbs. of carpet is operated on an economical, closed loop basis by initially providing, in the usual way, 3,500 gallons of water to a tank containing the carpet and adding thereto about 10 lbs. Lomar PW, 1 lb. of lgepal 630 (sold by General Analine & Film Corp.), as a surface active agent, and sufficient acetic acid to reduce the pH to about 5.0. The carpet is run for about 10 minutes and then about 20 lbs. of Sulfanin Red B dye (sold by Sandoz Chemical Co.) is slowly added over a ten minute period.

The dye bath is then run for about 10 more minutes and then heated to the boiling point thereof, approximately 205-2l0F, by introducing steam to raise the temperature at a rate of about 2F/minute. The quantity of steam ultimately added to increase the temperature of the treating bath from ambient temperature to the boiling point is about 400 gallons. After the dye bath has reached its boiling point, it is maintained at boiling for at least 30 minutes, until the proper shading has been reached. The carpeting is then separated from the dye bath solution which is dropped to a storage tank and the carpeting, after rinsing in water, is drained, squeezed and dried. Thereafter, about one half of the bath is dropped, and cold water is added to cool the carpeting to about l30-l40F. The carpeting is then run for a few minutes to level the temperature thereof. The bath is then completely dropped. Additional cold water is added and the carpet is run therein to rinse out unexhausted dye. The additional rinse water is then dropped and the rinsing step repeated until clear (generally once or twice more). The dye bath is refilled and, if necessary, softeners, jute dyeing, etc., is added, as well known, and the carpet run therein for 10-15 minutes until properly finished. The carpet is then removed and the remaining water is dropped.

The dropped water from each of the foregoing steps is conveyed to a central ditch to mix with water from prior or other batches. The waste water is conveyed to a 10,000 gallon treatment tank for regeneration. Approximately 3 lbs. of gaseous chlorine, is fed into the treatment tank. The chlorine, as previously described, provides hypochlorous acid which completely decolorizes the dyestuff and provides a small excess of chlorine. After the decolorization step, which takes place over approximately 1540 minutes, the decolorized solution is pumped to a 20,000 gallon storage tank. At the storage tank, which may have received decolorized solution from a different (or the same, but previously batched) treatment tank, any remaining chlorine is detected, e.g., by immersion of a potassium iodide-starch indicator strip. If there is excess chlorine, it is destroyed or neutralized by the addition of antichlor, in this case, sodium bisulfite.

Thereafter, the neutralized, treated waste water is fed into a dye bath as above and is used directly as a replacement for fresh water in all stages. Thus a portion is used in dyeing, a portion in rinsing, a portion in cooling, etc. Only a reduced amount, e.g., about 2.5 lbs. of make-up leveler is added. All other steps are identical to that for the initial processing. The process can be repeated indefinitely in the foregoing closed loop manner. A small amount of water is lost by evaporation and during drying, about 15-20 percent per cycle, and must be replaced.

In conducting the foregoing process, as has been previously mentioned, it can be applied to waste water contaminated by any of the known dyestuffs. Such dyestuffs include disperse, polyester disperse, acid, cationic and directs. Generally, the dyestuffs are used in a concentration of about 0.01-5 weight percent. The amount of leveling dyeing assistant used depends upon its type, to wit: nonionic'assistants at about 0.00l0.01 weight percent; anionic assistants at about 0.0251 weight percent; cationic assistants at about 0.5-1 .5 weight percent; and amphoteric assistants at about 0.5-1.5 weight percent.

It may be noted that the foregoing process reconstitutes dyes into levelers but the process can also be used with materials which do not require levelers. In such use the decolorized dye molecule represents merely a harmless diluent. Thus, the reclaimed waste water can be used to dye leather goods, cellulosic materials, synthetic and natural fibers and the like, in each instance reducing the overall cost of the dyeing process by a reduction or elimination of the cost of destroying dye molecules for decontamination purposes before passage of waste dye treating water to external sources.

Accordingly, improvement in a dyeing process for textiles and the like are provided which exhibit the advantages as described above. Various modifications,

changes and alterations in the steps of the process and l. A process for treating dyehouse waste water obtained from a textile dyeing process, for reclamation and reuse thereof, said textile dyeing process normally incorporating a levelling dyeing assistant and dye in a dye step thereof, said waste water comprising an aqueous solution of dyestuffs selected from the group consisting essentially acid and direct dyes, which process comprises:

placing said waste water into a treating tank;

adding a halogen selected from chlorine, bromine and iodine to said waste water in said treating tank in an amount equivalent to about 0.5-1.5 pounds of chlorine per 2500 gallons of said waste water sufficient to decolorize the chromophoric functional group of said dyestufi, retaining the site seeking substituents thereof and keeping said dyestuff otherwise intact, and then destroying any excess halogen, to form a reclaimed solution containing decolorized but otherwise intact dyestuff; and

using said decolorized dyestuff contained in said reclaimed solution in an acid or direct dyebath as a leveling dyeing assistant.

2. The process of claim 1 wherein said halogen is chlorine.

3. The process of claim 1 wherein said halogen is gaseous chlorine.

4. The process of claim 2 wherein said chlorine is destroyed by adding antichlor to said chlorine--containing waste water.

5. The process of claim 1 wherein said textile comprises carpeting.

6. The process of claim 1 wherein said process is a batch process. 

2. The process of claim 1 wherein said halogen is chlorine.
 3. The process of claim 1 wherein said halogen is gaseous chlorine.
 4. The process of claim 2 wherein said chlorine is destroyed by adding antichlor to said chlorine--containing waste water.
 5. The process of claim 1 wherein said textile comprises carpeting.
 6. The process of claim 1 wherein said process is a batch process. 